The explosion initially appeared to have been caused by a gas leak.

That explosion appears to have caused a large fracture in the dam.

He said the explosion appeared to be unplanned because of the timing.

The explosion appears to have been set next to a pod of liquid water.

He said the explosion appeared not to have been deliberately set off because of the timing.

He said the explosion appeared to be unplanned because of the time it occurred.

The explosion on Tuesday appeared to have been carefully planned and timed.

Later a local official said the explosions appeared to be the work of suicide bombers.

The authorities said the explosion appeared to be an accident, not the work of terrorists.

The safety board and the police said the explosion did not appear to be a terrorist act.